Following reports by concerned members that their water-efficient washing machines left detergent residue on their clothes, we decided to recreate the problem in our labs to work out how to deal with it.
The problem arises because some of the insoluble ingredients in detergents and some dirt don't get washed out when used with a low-water program. Normal CHOICE testing doesn't pick this up because the standard rinse performance test measures the soluble component of detergent that's left in the water after rinsing, not the insolubles. Also, our wash load is made up of white items (to best check the wash performance), which don't show up detergent residue well.
Our testers used various detergents for the test, washing black items in two water-efficient machines (the Fisher & Paykel Aquasmart WLT70T60C and the Miele W1712), to see which of the following produced the least residue:
- a powder detergent that was a poor performer in our last test
- a high-performing powder, both new and in a humidified state (simulating a packet having been open for a while)
- high-performing, clear top- and front-loading liquid detergents.
Only the high-performing liquid detergent didn't leave any residue on our test load. Alternatively, using half the recommended dose of the high-performance laundry powder, dissolved in warm water, also reduced the problem (our powder detergent test on the top-performing product showed that using between a half and quarter dose still produces a very good wash). Our testing has found that liquid detergent doesn't wash quite as well as powders. But if, like most people, your wash load isn't very dirty to start with, either option should get rid of detergent residue without compromising on wash performance.
Our testers also ran the Aquasmart on a 'traditional' wash – which uses twice the amount of water of the high-efficiency wash – and no residue was left behind. However, this defeats the purpose of buying a water-saving model in the first place.
We also asked the manufacturers about this issue.
What manufacturers said
Fisher & Paykel agreed that using a good-quality liquid detergent will reduce residue. They told us the problem tends to happen with very water-efficient machines, if you're using poor-quality or old detergent – and living in an area with very hard water can exacerbate the problem. They also suggested not buying detergent in bulk, because once opened it absorbs moisture, which lowers performance and can cause residue problems. As a last resort, Fisher & Paykel suggests switching to warm water washing, or a 'traditional' wash.
Miele says they don't receive complaints of this nature, but if you have experienced this problem they recommend choosing a wash program with a temperature of at least 30°C, which enables the detergent to dissolve. If you wash in cold, dissolving the powder in warm water first before pouring into the detergent dispenser is recommended; alternatively, use a good-quality liquid detergent. (This is why Miele doesn't have a cold wash setting for all programs. Miele's cold setting will still heat to 24°C on models that offer this setting in selected programs. The only Miele model that offers a true cold setting in the 'cottons' program is the W 3985 WPS).
Miele also says that a white powder residue left on dark clothing is not detergent residue but rather zeolite, a mineral now used in place of phosphates to soften water. Look out for a powder without zeolites to prevent this residue being left behind on dark garments.
Liquid detergents do not contain zeolites and are effective in hard water areas. Miele recommends using the 'dark garments' program, which has been designed not to leave this residue behind. Alternatively, a 'minimum iron' or 'automatic' program is also recommended, as these use more water in the wash and rinse process.
Other things that help:
- Store detergent in an airtight container to prevent it becoming clumpy, which can make the problem worse.
- Try putting the residue-affected clothes in a dryer on the 'air-dry' setting (that is, without heat, just using the fan) for five minutes. Some people have found this helps knock off the residue.
We tested the Fisher & Paykel Aquasmart in 2007 and found it performed well. However, members told us they experienced detergent residue being left behind when using this machine due to the small amount of water it used in the wash.
We tested for this, making suggestions on how to combat the fault without having to rerun the machine, and removed it from our What to Buy recommendations. We tested its replacement, the Fisher & Paykel WL80T65CW2 Aquasmart 2, running a few additional cycles to see whether it left residue behind on black clothing from the detergent. We found it doesn't, most probably from its increased water usage. We still don't recommend it for overall performance, however.
Unfortunately, another downside of front loaders (and water-efficient top loaders, for that matter) is that they often produce stiff, rough or scratchy towels. That's because the clothes are generally tumbling through just a little water rather than floating through lots of it, like in an older-style top loader. And to get the fibres nicely fluffed up, the clothes must be immersed in water.
Another reason could be that your front loader is, in fact, too water-efficient, in that it uses too little water for the rinse, leaving detergent residues in the wash. This is where we can help you choose a machine that's good at rinsing while still being water efficient – the water rating labels only tell you water use, not rinse efficiency.
Short of drying your towels for hours in an energy-guzzling clothes dryer to get them soft, you can try the following to help reduce their scratchy, flat effect.
- Add an extra rinse to your towels wash.
- Use a gentler program that uses more water.
- Lower the spin speed. Higher spin speeds tend to flatten the fibres and line drying doesn't fluff them back up, making them feel hard.
- Add half to one cup of white vinegar to the fabric softener dispenser (don't be tempted to use fabric softener, as this will lower the fabric's ability to absorb water).
- Shake your towels out vigorously, or put them in the dryer on the cooling cycle for a few minutes before hanging them out to dry.
- Take them off the line when still a little damp and dry them off in the dryer.
Miele's recommendation for this problem is to:
- Use the 'cottons' program with 'water plus' option and reduce the spin speed, or alternatively use the 'automatic' program.
- Use a good-quality liquid detergent for front loaders as well as fabric conditioner in the final rinse – Miele has found that good-quality fabric conditioners won't reduce the absorbency of the towels. Miele doesn't recommend the use of vinegar in the final rinse as its acidic nature can damage rubber components in the washing machine over time. If your laundry is stained, then add a liquid stain remover, such as Napisan Inwash liquid, to boost the efficiency of the detergent.
- Shake out the towels before putting them on the line or, alternatively, put them in the dryer on a cool setting for 10 minutes before hanging on the line. The tumbling action of the dryer will fluff the fibres back up, and minimal energy is used as the heating element is not switched on.
If you've had either of these problems, we'd love to hear about it in our comments section on how you deal with it and what works for you.